It is known in the control of internal combustion engines, particularly in industrial applications, to control engine load via an external generator. Such generators are typically electronically controlled and are responsive to at least a so-called "load bias" signal produced by electronic engine control circuitry to apply a corresponding load to the engine.
An example of a portion of a prior art control circuit 3 producing a steady state load bias signal (LB) is shown in FIG. 1. Control circuit 3 includes a load bias calculation block 5 receiving a commanded fueling (CF) signal and an engine speed (ES) signal, wherein block 5 is operable to produce the load bias signal LB as a function thereof. Conventionally, the load bias signal is determined by comparing ES with CF and producing LB as a signal proportional to where the current engine operation point is (typically in relation to an engine output power or torque curve or map) relative to an optimal operating point. The optimal rating point is typically determined as the most efficient engine power generated at a given engine speed.
While the prior art load bias signal LB provides for accurate and effective engine load control during steady state operating conditions, this accuracy and efficacy diminishes during transient operating conditions. For example, during engine acceleration conditions, if the load bias signal LB is directly followed it results in less than optimal or sluggish engine performance. Optimal engine acceleration is dependent on the amount of air (boost pressure) and fuel available to the engine at any given engine speed.
Likewise, during deceleration of the engine, if the load bias curve is directly followed it results in less than optimal engine performance. The load bias signal in this case will request more load as the engine is decelerating, as the requested fueling is very low during deceleration conditions (i.e. the operator lets up on the throttle). The engine accordingly decelerates at the same time that the load bias signal is requesting more loading, which results in excessive loading on the engine when the target engine RPM is reached. This typically results in the target RPM being overshot, which is an undesirable engine response.
What is therefore needed is a system for improving the load bias signal LB to provide optimal engine performance not only during steady state engine operating conditions, but also during transient engine operating conditions such as during engine acceleration and deceleration.